Portable consumer electronics such as cellular phones, netbooks, tablets, and portable games can be enhanced with mechanical feedback to stimulate the user. A couple of examples would be vibration from a motor or haptic feedback from a piezoelectric transducer. The addition of some form of physical stimulation makes the product much more attractive. Engineers are constantly trying to invent and/or develop some form of material to help create physical stimulation. As a result, an electroactive polymer, developed by Artificial Muscle Inc, can be used to generate haptic mechanical feedback. The material requires an analog voltage up to 500 Hz with an amplitude of 1000V. The electrical behavior of the material is mainly capacitive of about 2 nF. Another company, Senseg, develop a material based on electro-sensory effects to generate haptic feedback by Coulomb force. The material requires digital pulses up to 500 Hz with an amplitude of 3000V. The electrical behavior of this material is also mainly capacitive of about 500 pF.
The high voltages required to drive these materials are not readily available in battery powered portable equipment. Any circuitry for portable electronics should be physically as small as possible. Portable consumer electronics are commonly powered by lithium batteries which has an operating voltage range of about 3.0V to 4.2V. Therefore, a circuit topology that is physically small, operates from a low voltage source, such as a single lithium cell battery, and generates an output that can be either a high voltage analog waveform or high voltage digital pulses is therefore warranted.